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  • CVE-2012-3410 stack-based buffer overflow vulnerability in Bash

    - by RitwikGhoshal
    CVE DescriptionCVSSv2 Base ScoreComponentProduct and Resolution CVE-2012-3410 Buffer overflow vulnerability 4.6 Bash Solaris 11 Contact Support Solaris 10 SPARC: 126546-04 X86: 126547-04 Solaris 9 Contact Support This notification describes vulnerabilities fixed in third-party components that are included in Oracle's product distributions.Information about vulnerabilities affecting Oracle products can be found on Oracle Critical Patch Updates and Security Alerts page.

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  • the web technology stack is too deep [closed]

    - by AgostinoX
    A standard state-of-the-art project requires at least jsf + spring + faces palette + orm. That's a lot of stuff. Also frameworks like spring misses to bring to the point of starting developing. Otherwise, things like spring-roo wuoldn't even exist. The solution to this may be buy support. Have dedicated people doing integration. Switch to ruby on rails. Switch to dot.net. Since this is a problem, I'm intrested in HOW people address this (java ee) specific concern.

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  • Donate Your Old Hardware

    <b>System 76:</b> "System76 has partnered with a non-profit, Kids on Computers, to help bring computers and free and open source software to disadvantaged kids."

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  • Circular motion on low powered hardware

    - by Akroy
    I was thinking about platforms and enemies moving in circles in old 2D games, and I was wondering how that was done. I understand parametric equations, and it's trivial to use sin and cos to do it, but could an NES or SNES make real time trig calls? I admit heavy ignorance, but I thought those were expensive operations. Is there some clever way to calculate that motion more cheaply? I've been working on deriving an algorithm from trig sum identities that would only use precalculated trig, but that seems convoluted.

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  • Ubuntu Enterprise Cloud Deployed on Intel Hardware

    <b>Softpedia:</b> "Canonical, the company behind the very popular Ubuntu Linux distribution, recognizes the potential of the emerging market and has partnered with Intel and Eucalyptus to promote its Ubuntu Enterprise Cloud (UEC) offering as part of Intel's Cloud Builder program."

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  • The Simplicity of the Oracle Stack

    - by user801960
    For many retailers, technology is something they know they need to optimise business operations, but do they really understand it and how can they select the solutions they need from the many vendors on the market? Retail is a data heavy industry, with the average retailer managing thousands of SKUs and hundreds of categories through multiple channels. Add to this the exponential growth in data driven by social media and mobile activities, and the process can seem overwhelming. Handling data of this magnitude and analyzing it effectively to gain actionable insight is a huge task, and needs several IT components to work together harmoniously to make the best use of the data available and make smarter decisions. With this in mind, Oracle has produced a video to make it easier for businesses to understand its global data IT solutions and how they integrate seamlessly with Oracle’s other solutions to enable organisations to operate as effectively as possible. The video uses an orchestra as an analogy for IT solutions and clever illustration to demonstrate the value of the Oracle brand. This video can be viewed at http://medianetwork.oracle.com/video/player/1622148401001. To find out more about how Oracle’s products and services can help retailers to deliver better results, visit the Oracle Retail website.

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  • vagrant fails to bring up additional adapter for centos vm using virtual box provider

    - by Anadi Misra
    this is in continuation of the question asked here about host only adapter on dhcp I upgraded to vagrant 1.6.3 and the updated Vagrantfile to following setting for multiple adapters # add additional adapter for inter machine networking dev.vm.network :private_network, :type => "dhcp", :adapter => "2", :netmask => "255.255.255.0" it goes through creating adapters but then fails bringing up the mic on vm Anadis-MacBook-Pro:full-stack-env anadi$ vagrant up Bringing machine 'full-stack-env' up with 'virtualbox' provider... ==> full-stack-env: Clearing any previously set forwarded ports... ==> full-stack-env: Clearing any previously set network interfaces... ==> full-stack-env: Preparing network interfaces based on configuration... full-stack-env: Adapter 1: nat full-stack-env: Adapter 2: hostonly ==> full-stack-env: Forwarding ports... full-stack-env: 22 => 4223 (adapter 1) full-stack-env: 8080 => 8090 (adapter 1) ==> full-stack-env: Running 'pre-boot' VM customizations... ==> full-stack-env: Booting VM... ==> full-stack-env: Waiting for machine to boot. This may take a few minutes... full-stack-env: SSH address: 127.0.0.1:4223 full-stack-env: SSH username: vagrant full-stack-env: SSH auth method: private key full-stack-env: Warning: Connection timeout. Retrying... full-stack-env: Warning: Connection timeout. Retrying... full-stack-env: Warning: Remote connection disconnect. Retrying... ==> full-stack-env: Machine booted and ready! ==> full-stack-env: Checking for guest additions in VM... ==> full-stack-env: Setting hostname... ==> full-stack-env: Configuring and enabling network interfaces... The following SSH command responded with a non-zero exit status. Vagrant assumes that this means the command failed! ARPCHECK=no /sbin/ifup eth 2> /dev/null Stdout from the command: Device eth does not seem to be present, delaying initialization. Stderr from the command: how ever when I log in to the environment I see two network interfaces as expected Anadis-MacBook-Pro:full-stack-env anadi$ vagrant ssh Last login: Wed Jun 4 12:54:47 2014 from 10.0.2.2 [vagrant@full-stack-env ~]$ ifconfig eth0 Link encap:Ethernet HWaddr 08:00:27:BD:39:57 inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:febd:3957/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:511 errors:0 dropped:0 overruns:0 frame:0 TX packets:360 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:54574 (53.2 KiB) TX bytes:46675 (45.5 KiB) eth1 Link encap:Ethernet HWaddr 08:00:27:A3:86:C9 inet addr:172.28.128.3 Bcast:172.28.128.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fea3:86c9/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5 errors:0 dropped:0 overruns:0 frame:0 TX packets:9 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1360 (1.3 KiB) TX bytes:894 (894.0 b) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) I am bit confused here on why it is trying to add another mic (eth2)? In the VM I used for creating this vagrant box, I had added two NICs already.

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  • Phonon - Audio Hardware Setup

    - by Michael
    Does anyone know what configuration file is modified when I change settings within this area of the system settings? I keep choosing my Logitech USB Headset as the soundard, and, when I hit apply, it accepts that change and all is good. However, as soon as I close the system settings window, it loses the setting, so I have to leave it open all the time. How can I make this setting permanent? Thanks for any assistance. I'm actually running Kubuntu 11.10.

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  • OOW 12: Hardware and Software Engineered to Work Together

    - by kellsey.ruppel
    If you were among the thousands of folks that filled the Moscone Center Hall D last night to hear Larry Ellison’s keynote, this will be old news to you.  If you weren’t able to catch the session, Larry covered Oracle’s fundamentally different approach to delivering technology that is engineered to work together to give customers extreme performance, simplicity, and cost savings. As you many know, innovating for growth requires the right investments and the right technology. And Oracle is equipped and ready. If you are attending Oracle OpenWorld, you’ll want to be sure you don’t miss out on any of the following activities! Oracle OpenWorld Music Festival Oracle WebCenter Customer Appreciation Reception | Tues, Oct 2 | 6:30pm-9:30pm | RSVP Oracle WebCenter Strategy & Vision | Mon, Oct 1 | 10:45am-11:45am Oracle WebCenter Focus On Guide | Events, Activities, Hands on Labs & More!

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  • SQL Server Hardware Configuration Best Practices

    You have been asked to deploy a brand new SQL Server instance. Your management asks you to come up with the best balance of availability, performance and cost for SQL Server. Richard Vantrease has some recommendations. Get to grips with SQL Server replicationIn this new eBook Sebastian Meine gives a hands-on introduction to SQL Server replication, including implementation and security. Download free ebook now.

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  • Graphics hardware warning when updating to 14.04

    - by pacomet
    As I use Ubuntu at work I just update only LTS versions but now I'm not sure if I can/should. As my computer is now ten years old I would change if was mine but as it is owned by my employer I have to work with it. It's not a bad one, it runs fine (this was not true when still had Windows on it ;-). When updating to 14.04, it warns about possible bad/slow performance with Unity 3D so I stop updating as I am at work, not my own computer. As I understand from http://askubuntu.com/a/438958/25305 Nvidia Geforce FX 5500 graphics card is still supported in 14.04. Now, in 12.04, I have driver version 173 and unity 2d runs fine for me. output of /usr/lib/nux/unity_support_test -p OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: GeForce FX 5500/AGP/SSE2 OpenGL version string: 2.1.2 NVIDIA 173.14.39 Not software rendered: yes Not blacklisted: no GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: no Should I update? Is it better to stay with 12.04? Thanks

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  • Unable to use Hardware Acceleration for Radeon HD 6490M card

    - by user62004
    I've followed steps in this guide. Here is output of 'vainfo' command: libva: VA-API version 0.32.0 libva: va_getDriverName() returns 0 libva: Trying to open /usr/lib/x86_64-linux-gnu/dri/i965_drv_video.so libva: va_openDriver() returns -1 vaInitialize failed with error code -1 (unknown libva error),exit I have Catalyst 12.6 driver installed (from debs). Also I've fixed switchable graphics bug, using this guide (STEP 2). I've tried to add 'LIBVA_DRIVER_NAME=xvba LIBVA_DRIVERS_PATH=/usr/lib/va/drivers' to /etc/environment and rebooted system, but the result was the same. PLEASE HELP! :) Thanks! :]

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  • Change Keybindings (hardware to software)

    - by Daniel
    I ran a search for this, but the answers I saw were referring to something altogether different than what I'm asking for. So let me clarify: I'm not asking how to change key-combo shortcuts. I'm asking--how do you actually change what your computer thinks you did when you press a given key? An example of what I mean (and the reason I'm asking). I'm a Chrome user, and I use Windows alongside Ubuntu. I own a Lenovo Thinkpad T61p--it came with my scholarship package, and I would have shopped for a nice computer if I could have. The T61p has two buttons above the left and right arrow keys that relate to browser commands to go back and forth one page. This is extremely frustrating for me, as I use the arrow keys, and a single accidental keystroke will catch me going back a page, losing temporary data, and yelling at my stupid keyboard. At the same time, I'm the type of person who keeps way too many tabs open. Chrome doesn't let me refigure keyboard shortcuts, and the only way it allows you to switch between tabs are ctrl+tab and ctrl+shift+tab, and ctrl+page up/down. I was using Notepad++, and they had finally found the solution to both problems! The page back and forth keys functioned as tab back and forth keys. I went through quite some effort to learn how to change the keybindings in Windows. The page back and page forward keys are now the page up and page down keys, respectively, and if I hit control, they let me switch tabs easily, and rather pleasantly. And if I hit the keys by accident, no harm, no foul. Alas, I'm in Ubuntu now, and I need to go through the process again. And while I couldn't just find the answer online, like I did for Windows, I know Ubuntu has nice, supportive communities like this one, where, hopefully, somebody can tell me how to do either what I did in Windows, or directly make it so that my computer changes tabs when I hit those buttons (removing the ctrl button from the tab-changing command).

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  • Useful programming languages for hardware programming

    - by Sebastian Griotberg
    I am thinking to take the next semester a course called "Digital systems architecture", and I know that we need to program micro-controllers with several programming languages such as C, C++, verilog, and VHDL. I want to be prepared to take that course, but I need to know if I need to study deeper these languages. At this moment, I have taken one course in basic Java dealing with basic methods, data types, loop structures, vectors, matrices, and GUI programing. Must I study deeper Java and then go with C, and C++? Besides, I know basic verilog and VHDL.

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  • Hardware problem

    - by Ajay0990
    Guys I need help to recover my external hard disk. Im using SEGATE FREEAGENT GO 320gb HDD. Recently I tried to format it using command line in win7, but accidentally I removed the hdd before the format is complete and I cannot open it and I tried to recover data using as many software's as I can but no use I have max of 25000 bad sectors. Can i still recover my hdd? Is there any way to recover my HDD with max bad sectors using Linux?

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  • UEFI hardware and dual booting with windows

    - by user39803
    I've been struggling for 3 days trying to dual boot Ubuntu 11.10 and Windows 7. I want to use an SSD for my Ubuntu installation and an hdd for Windows. I realized that I have to install windows first and then ubuntu, and so I did that. When I first install windows it boots fine from my hdd, but when I add ubuntu on my ssd and restart, I get a black screen with a blinking cursor. I've read many forums where this is asked but haven't found a single solution that works. I've tried boot repair. It told me to make a fat ESP partition and I did that as well but it still doesn't work. I'm a noob and any suggestions would be really appreciated.

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  • Ubuntu 14.04 install on hardware with RAID

    - by nolak
    I've just built a new machine using an ASUS Mobo with 8GB of RAM and set up RAID 10 with 4 new HDD. I want to install Ubuntu 14.04 on it and so far have tried to do so 3 times with no luck. The installation seems to work fine but after it has finished it restarts and all I get is a black screen. Is there something I am missing? I've completed the install on other machines before without issue I just never tried it on a machine with RAID set up.

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  • Design by Contract with Microsoft .Net Code Contract

    - by Fredrik N
    I have done some talks on different events and summits about Defensive Programming and Design by Contract, last time was at Cornerstone’s Developer Summit 2010. Next time will be at SweNug (Sweden .Net User Group). I decided to write a blog post about of some stuffs I was talking about. Users are a terrible thing! Protect your self from them ”Human users have a gift for doing the worst possible thing at the worst possible time.” – Michael T. Nygard, Release It! The kind of users Michael T. Nygard are talking about is the users of a system. We also have users that uses our code, the users I’m going to focus on is the users of our code. Me and you and another developers. “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler Good programmers also writes code that humans know how to use, good programmers also make sure software behave in a predictable manner despise inputs or user actions. Design by Contract   Design by Contract (DbC) is a way for us to make a contract between us (the code writer) and the users of our code. It’s about “If you give me this, I promise to give you this”. It’s not about business validations, that is something completely different that should be part of the domain model. DbC is to make sure the users of our code uses it in a correct way, and that we can rely on the contract and write code in a way where we know that the users will follow the contract. It will make it much easier for us to write code with a contract specified. Something like the following code is something we may see often: public void DoSomething(Object value) { value.DoIKnowThatICanDoThis(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Where “value” can be uses directly or passed to other methods and later be used. What some of us can easily forget here is that the “value” can be “null”. We will probably not passing a null value, but someone else that uses our code maybe will do it. I think most of you (including me) have passed “null” into a method because you don’t know if the argument need to be specified to a valid value etc. I bet most of you also have got the “Null reference exception”. Sometimes this “Null reference exception” can be hard and take time to fix, because we need to search among our code to see where the “null” value was passed in etc. Wouldn’t it be much better if we can as early as possible specify that the value can’t not be null, so the users of our code also know it when the users starts to use our code, and before run time execution of the code? This is where DbC comes into the picture. We can use DbC to specify what we need, and by doing so we can rely on the contract when we write our code. So the code above can actually use the DoIKnowThatICanDoThis() method on the value object without being worried that the “value” can be null. The contract between the users of the code and us writing the code, says that the “value” can’t be null.   Pre- and Postconditions   When working with DbC we are specifying pre- and postconditions.  Precondition is a condition that should be met before a query or command is executed. An example of a precondition is: “The Value argument of the method can’t be null”, and we make sure the “value” isn’t null before the method is called. Postcondition is a condition that should be met when a command or query is completed, a postcondition will make sure the result is correct. An example of a postconditon is “The method will return a list with at least 1 item”. Commands an Quires When using DbC, we need to know what a Command and a Query is, because some principles that can be good to follow are based on commands and queries. A Command is something that will not return anything, like the SQL’s CREATE, UPDATE and DELETE. There are two kinds of Commands when using DbC, the Creation commands (for example a Constructor), and Others. Others can for example be a Command to add a value to a list, remove or update a value etc. //Creation commands public Stack(int size) //Other commands public void Push(object value); public void Remove(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   A Query, is something that will return something, for example an Attribute, Property or a Function, like the SQL’s SELECT.   There are two kinds of Queries, the Basic Queries  (Quires that aren’t based on another queries), and the Derived Queries, queries that is based on another queries. Here is an example of queries of a Stack: //Basic Queries public int Count; public object this[int index] { get; } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To understand about some principles that are good to follow when using DbC, we need to know about the Commands and different Queries. The 6 Principles When working with DbC, it’s advisable to follow some principles to make it easier to define and use contracts. The following DbC principles are: Separate commands and queries. Separate basic queries from derived queries. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries. For each command, write a postcondition that specifies the value of every basic query. For every query and command, decide on a suitable precondition. Write invariants to define unchanging properties of objects. Before I will write about each of them I want you to now that I’m going to use .Net 4.0 Code Contract. I will in the rest of the post uses a simple Stack (Yes I know, .Net already have a Stack class) to give you the basic understanding about using DbC. A Stack is a data structure where the first item in, will be the first item out. Here is a basic implementation of a Stack where not contract is specified yet: public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } //Is related to Count and this[] Query public object Top() { return this[Count]; } //Creation commands public Stack(uint size) { Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { this[++Count] = value; } public void Remove() { this[Count] = null; Count--; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The Stack is implemented in a way to demonstrate the use of Code Contract in a simple way, the implementation may not look like how you would implement it, so don’t think this is the perfect Stack implementation, only used for demonstration.   Before I will go deeper into the principles I will simply mention how we can use the .Net Code Contract. I mention before about pre- and postcondition, is about “Require” something and to “Ensure” something. When using Code Contract, we will use a static class called “Contract” and is located in he “System.Diagnostics.Contracts” namespace. The contract must be specified at the top or our member statement block. To specify a precondition with Code Contract we uses the Contract.Requires method, and to specify a postcondition, we uses the Contract.Ensure method. Here is an example where both a pre- and postcondition are used: public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The contract above requires that the Count is greater than 0, if not we can’t get the item at the Top of a Stack. We also Ensures that the results (By using the Contract.Result method, we can specify a postcondition that will check if the value returned from a method is correct) of the Top query is equal to this[Count].   1. Separate Commands and Queries   When working with DbC, it’s important to separate Command and Quires. A method should either be a command that performs an Action, or returning information to the caller, not both. By asking a question the answer shouldn’t be changed. The following is an example of a Command and a Query of a Stack: public void Push(object value) public object Top() .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The Push is a command and will not return anything, just add a value to the Stack, the Top is a query to get the item at the top of the stack.   2. Separate basic queries from derived queries There are two different kinds of queries,  the basic queries that doesn’t rely on another queries, and derived queries that uses a basic query. The “Separate basic queries from derived queries” principle is about about that derived queries can be specified in terms of basic queries. So this principles is more about recognizing that a query is a derived query or a basic query. It will then make is much easier to follow the other principles. The following code shows a basic query and a derived query: //Basic Queries public uint Count; //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   We can see that IsEmpty will use the Count query, and that makes the IsEmpty a Derived query.   3. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries.   When the derived query is recognize we can follow the 3ed principle. For each derived query, we can create a postcondition that specifies what result our derived query will return in terms of one or more basic queries. Remember that DbC is about contracts between the users of the code and us writing the code. So we can’t use demand that the users will pass in a valid value, we must also ensure that we will give the users what the users wants, when the user is following our contract. The IsEmpty query of the Stack will use a Count query and that will make the IsEmpty a Derived query, so we should now write a postcondition that specified what results will be returned, in terms of using a basic query and in this case the Count query, //Basic Queries public uint Count; //Derived Queries public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } The Contract.Ensures is used to create a postcondition. The above code will make sure that the results of the IsEmpty (by using the Contract.Result to get the result of the IsEmpty method) is correct, that will say that the IsEmpty will be either true or false based on Count is equal to 0 or not. The postcondition are using a basic query, so the IsEmpty is now following the 3ed principle. We also have another Derived Query, the Top query, it will also need a postcondition and it uses all basic queries. The Result of the Top method must be the same value as the this[] query returns. //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count and this[] Query public object Top() { Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   4. For each command, write a postcondition that specifies the value of every basic query.   For each command we will create a postconditon that specifies the value of basic queries. If we look at the Stack implementation we will have three Commands, one Creation command, the Constructor, and two others commands, Push and Remove. Those commands need a postcondition and they should include basic query to follow the 4th principle. //Creation commands public Stack(uint size) { Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   As you can see the Create command will Ensures that Count will be 0 when the Stack is created, when a Stack is created there shouldn’t be any items in the stack. The Push command will take a value and put it into the Stack, when an item is pushed into the Stack, the Count need to be increased to know the number of items added to the Stack, and we must also make sure the item is really added to the Stack. The postconditon of the Push method will make sure the that old value of the Count (by using the Contract.OldValue we can get the value a Query has before the method is called)  plus 1 will be equal to the Count query, this is the way we can ensure that the Push will increase the Count with one. We also make sure the this[] query will now contain the item we pushed into the Stack. The Remove method must make sure the Count is decreased by one when the top item is removed from the Stack. The Commands is now following the 4th principle, where each command now have a postcondition that used the value of basic queries. Note: The principle says every basic Query, the Remove only used one Query the Count, it’s because this command can’t use the this[] query because an item is removed, so the only way to make sure an item is removed is to just use the Count query, so the Remove will still follow the principle.   5. For every query and command, decide on a suitable precondition.   We have now focused only on postcondition, now time for some preconditons. The 5th principle is about deciding a suitable preconditon for every query and command. If we starts to look at one of our basic queries (will not go through all Queries and commands here, just some of them) the this[] query, we can’t pass an index that is lower then 1 (.Net arrays and list are zero based, but not the stack in this blog post ;)) and the index can’t be lesser than the number of items in the stack. So here we will need a preconditon. public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Think about the Contract as an documentation about how to use the code in a correct way, so if the contract could be specified elsewhere (not part of the method body), we could simply write “return _array[index]” and there is no need to check if index is greater or lesser than Count, because that is specified in a “contract”. The implementation of Code Contract, requires that the contract is specified in the code. As a developer I would rather have this contract elsewhere (Like Spec#) or implemented in a way Eiffel uses it as part of the language. Now when we have looked at one Query, we can also look at one command, the Remove command (You can see the whole implementation of the Stack at the end of this blog post, where precondition is added to more queries and commands then what I’m going to show in this section). We can only Remove an item if the Count is greater than 0. So we can write a precondition that will require that Count must be greater than 0. public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   6. Write invariants to define unchanging properties of objects.   The last principle is about making sure the object are feeling great! This is done by using invariants. When using Code Contract we can specify invariants by adding a method with the attribute ContractInvariantMethod, the method must be private or public and can only contains calls to Contract.Invariant. To make sure the Stack feels great, the Stack must have 0 or more items, the Count can’t never be a negative value to make sure each command and queries can be used of the Stack. Here is our invariant for the Stack object: [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The ObjectInvariant method will be called every time after a Query or Commands is called. Here is the full example using Code Contract:   public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } set { Contract.Requires(index >= 1); Contract.Requires(index <= Count); _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } //Is related to Count and this[] Query public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } //Creation commands public Stack(uint size) { Contract.Requires(size > 0); Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Requires(value != null); Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Summary By using Design By Contract we can make sure the users are using our code in a correct way, and we must also make sure the users will get the expected results when they uses our code. This can be done by specifying contracts. To make it easy to use Design By Contract, some principles may be good to follow like the separation of commands an queries. With .Net 4.0 we can use the Code Contract feature to specify contracts.

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  • x86_64 Assembly Command Line Arguments

    - by Brandon oubiub
    I'm new to assembly, and I just got familiar with the call stack, so bare with me. To get the command line arguments in x86_64 on Mac OS X, I can do the following: _main: sub rsp, 8 ; 16 bit stack alignment mov rax, 0 mov rdi, format mov rsi, [rsp + 32] call _printf Where format is "%s". rsi gets set to argv[0]. So, from this, I drew out what (I think) the stack looks like initially: top of stack <- rsp after alignment return address <- rsp at beginning (aligned rsp + 8) [something] <- rsp + 16 argc <- rsp + 24 argv[0] <- rsp + 32 argv[1] <- rsp + 40 ... ... bottom of stack And so on. Sorry if that's hard to read. I'm wondering what [something] is. After a few tests, I find that it is usually just 0. However, occasionally, it is some (seemingly) random number. EDIT: Also, could you tell me if the rest of my stack drawing is correct?

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  • Gathering buslogic SCSI hardware and virtual machine operating system

    - by Julian
    I'm trying to use Powershell to get SCSI hardware from several virtual servers and get the operating system of each specific server. I've managed to get the specific SCSI hardware that I want to find with my code, however I'm unable to figure out how to properly get the operating system of each of the servers. Also, I'm trying to send all the data that I find into a csv log file, however I'm unsure of how you can make a powershell script create multiple columns. Here is my code (almost works but something's wrong): $log = "C:\Users\me\Documents\Scripts\ScsiLog.csv" Get-VM | Foreach-Object { $vm = $_ Get-ScsiController -VM $vm | Where-Object { $_.Type -eq "VirtualBusLogic" } | Foreach-Object { get-VMGuest -VM $vm } | Foreach-Object{ Write-output $vm.Guest.VmName >> $log } } I don't receive any errors when I run this code however whenever I run it I'm only getting the name of the servers and not the OS. Also I'm not sure what I need to do to make the OS appear in a different column from the name of the server in the csv log that I'm creating. What do I need to change in my code to get the OS version of each virtual machine and output it in a different column in my csv log file? EDIT: Here's a more in depth look at things I've tried that have all failed: Get-VM | Foreach-Object { $vm = $_ $svm = Get-ScsiController -VM $vm | Where-Object { $_.Type -eq "VirtualBusLogic" } Foreach-Object {get-VMGuest -VM $svm } | Foreach-Object{Write-output $svm >> $log} } #Get-VM | Foreach-Object { # $vm = $_ # Get-ScsiController -VM $vm | Where-Object { $_.Type -eq "VirtualBusLogic"} #| write-host $vm # | Foreach-Object { # # #get-VMGuest -VM $_ | # #write-host $vm # #get-VMGuest -VM $vm } | Foreach-Object{ # #write-output $vm.VmName >> $log # #write-output $vm.guest.VmName, get-VmGuest -VM $vm >> $log NO GOOD # # Write-host $vm.Guest.VmName #+ get-vmGuest -vm $VM >> $log # # # } # } I'm not sure why get-VmGuest fails though. I'm getting the scsi hardware, filtering the hardware to only get buslogic, and then wanting to get the operating system of just the filtered VMs. I don't see where my code fails though.

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  • Complete stack traces from Hyperic

    - by Mike Kushner
    I've setup Hyperic to run on our CI-machine, and every once in a while it reacts to some random stack trace and sends of an alert. So far so good, we've caught a lot of intermittent bugs that way. My only issue is that the alert only contains the first error line and not the entire stack trace, which requires me to access the machine and look at the logs manually. Is there any way to modify the alert message to contain more information, alternatively to include the log file in the alert mail?

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